VeriFast
TM
LVDT – User Manual – FDP-VFA-LVD-UM-EL-1.15-0918
11
Equipment and Process Overview
Intended Use of Equipment
The VeriFast LVDT is a component of a resistance welding system. When properly installed in
conjunction with resistance weld control equipment and used within the system’s specification
limits, the VeriFast LVDT is used to verify the presence and orientation of fasteners or materials.
The VeriFast LVDT is not intended for any other use.
The VeriFast LVDT sensor signal is calibrated to measure and output the position of the
fastener (nut or stud) weld pin in various stages of travel. The values of this signal are then
compared to peripherally programmed set point values (with tolerances). Results that do not
match the set point values can trigger either an interruption in the cycle, or a warning message
indicating that the process has fallen outside the set value. These occurrences can indicate a
potential part quality issue.
The set point values may indicate:
•
Weld Pin Extended Position (System ready to load part and fastener)
•
Weld Proceed (Presence and Correct Fastener Orientation)
•
Weld Complete (Nut Welded)
•
Nut is Upside Down
•
No Fastener Detected
•
No Part Detected
•
Weld Pin Retracted Position (Allowing safe part removal by robot or other process operations)
The VeriFast LVDT system has the ability to detect differences as small as
(0.02 mm) 0.0009".
However, actual performance is dependent on the effective resolution of the control system to
which it is integrated. For more information refer to section
Determining Effective Resolution
page 24.
The following example shows a nut application. It demonstrates the difference between correct
fastener orientation, and other error conditions.
